When they are world's largest state sponsor of terror, are directly responsible for the deaths of American service members, and are trying to develop nuclear weapons, no it's not right to give them access to $6 billion. Especially when using the money to trade for hostages.
On the other hand...think about it:
The U.S. overthrew a legitimate Iranian government and installed a corrupt, ruthless dictator who ran a sadistic and merciless security system in Iran.
The U.S. developed the atomic bomb and dropped it on two Japanese cities. The U.S has an arsenal of thousands of nuclear warheads.
The U.S. used baseless information to justify an invasion of a sovereign nation (Iraq and later Afghaniststan) which resulted in the deaths of hundreds of thousands in a twenty year war. The U.S. then abandoned it's supporters in Afghanistan and caused the death of many U.S. soldiers in an inept withdrawal.
The U.S. holds foreign citizens in prison in Guantanamo Bay without trial.
The U.S. sent foreign nationals to Romania for interrogation to avoid U.S. laws.
The U.S. has overthrown numerous legitimate South American governments and installed puppet regimes.
The U.S. supports Saudi Arabia which is a ruthless dictatorship. SA nationals attacked the U.S. on 9/11.
Saudi Arabia has assassinated those who speak out.